(a) Field of the Invention
The present disclosure relates to a mobile communication system for providing carrier aggregation between digital units, and a method for processing a signal in the system.
(b) Description of the Related Art
In general, in a communication base station, a digital signal processing unit (hereinafter, referred to as a “digital unit (DU)”) and a radio signal processing unit (hereinafter, referred to as a “radio unit (RU)”) are included in a single physical system. However, in such a system, a base station including all of processing units should be installed in a cell, thereby having a limitation in optimization of designing a cell. Thus it is difficult to improve radio capacity. In order to solve the problem, only an antenna component and an RF component processing a radio signal are remotely separated to form a radio unit (RU), and a plurality of RUs are connected to a single digital unit (DU).
Recently, radio communication technologies have rapidly advanced, and communication system technologies have also rapidly evolved. Among them, a long term evolution (LTE) system has come to prominence as a 4th-generation mobile communication technology. In the LTE system, various technologies, including carrier aggregation (CA), have been introduced to meet exploding traffic demand. CA is a technique of using a primary carrier and one or a plurality of secondary carriers, rather than using only a single carrier between a terminal and a base station in a typical communication system, whereby a transmission amount may significantly increase to correspond to the number of secondary carriers.
For example, CA is available between different frequencies by connecting a plurality of RUs having different center frequencies to a single DU.
However, CA is possible only for RUs connected to the same DU and supporting different frequencies. That is, CA is not possible between RUs connected to different DUs and supporting different frequencies.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.